Anti-swing damping means for cranes



June 7, 1966 R. L. BEVARD ETAL ANTI-SWING DAMPING MEANS FOR CRANES 4 Sheets-Sheet 1 Filed May 16, 1963 INVENTORS. flit 4Z0 Nw\ NWW N 5 5; 5;

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June 7, 1966 R. L. BEVARD ETAL ANTI-SWING DAMPING MEANS FOR CRANES 4 Sheets-Sheet 2 Filed May 16, 1963 R n O E m 5 4 z 5 W m June 7, 1966 R. L. BEVARD ETAL 3,254,775

ANTI SWING DAMPING' MEANS FOR CRANES 4 Sheets-Sheet 3 Filed May 16, 1963 INVENTORS. lfaze 621 0 lrrazwzy June 7, 1966 R. L. BEVARD ETAL 3,254,775

ANTI-SWING DAMPING MEANS FOR CRANES Filed May 16 1965 4 Sheets-Sheet 4 United States Patent 3,254 775 ANTI-SWING DAMPING MEANS F612 CRANES Roger L. Bevard and Lawrence S. Commora, Iron Mountain, Mich, assignors to Lake Shore, [11%, Iron Mountain, Mich, a corporation of Michigan Filed May 16, 1963, Ser. No. 280,972 11 Claims. (Cl. 21214) This invention relates to load handling apparatus such as a shipboard crane.

One of the principal objects of this invention is to provide a swing damping and load leveling arrangement which is usable with load handling apparatus including either spreader or hook-type load engaging means.

Another object of this invention is to provide an improved arrangement for damping swinging movement of the load and load engaging means of load handling apparatus.

A further object of this invention is to provide an improved arrangement for leveling or adjusting the load and load engaging means with respect to a shipboard crane.

Still another object of this invention is to provide in creased surveillance and control over loading and unload engaging means with respect to a shipboard crane.

A more general object of this invention is to provide the above objects while maintaining a relatively simple and economical shipboard crane construction.

Generally, shipboard cranes incorporate either spreader or hook-type load engaging means and conditions which are encountered, and which must be corrected for, during crane operation are a swinging load and carrying on a loading, or unloading, operation from a listing ship. Swinging loads are primarily of concern where hook-type load engaging means is used, whereas, a listing ship is primarily of concern where a spreader is used.- As stated above, a general object of this invention is to provide an improved arrangement for use in combination with a hook to damp swinging movement thereof or for use with a spreader-to adjust the horizontal position of the load carried by the spreader when operating from a listing ship. To this end, an assembly is provided for cooperation with the hoist cables of the shipboard crane, the assembly including a damping mechanism which is effective to damp swinging movement of the load and also including a leveling mechanism which is operative to adjust the level of the load relative to the shipboard crane. By providing a crane with an assembly which includes both the damping and the leveling mechanisms, the crane has universal applicability to use with both spreader and hook-type load-engaging means; however, it will be appreciated that only one or the other of the damping and leveling mechanisms could be included. By providing an arrangement whereby both the damping and leveling mechanisms operate through manipulation of the hoist cables a versatile, compact and particularly effective assembly is provided. In another aspect of this invention, increased surveillance over the leveling and damping mechanism, as well as over the loading and unloading operations of the shipboard crane is achieved through the provision of a control cab which is supported for independent movement on the crane so that it can be driven along the crane to assume any desired position.

Other objects and advantages will be pointed out in, or be apparent from, the specification and claims, as will obvious modifications of the embodiments shown in the drawings, in which:

FIG. 1 is an end view of a typical installation;

FIG. 2 is an athwartship view of the installation;

FIG. 3 is a top plan view of the load handling apparatus;

FIG. 4 is a partial perspective view of the load handling apparatus;

Patented June 7, 1966 'ice I FIG. 4a is a slightly enlarged view of the swing damping and leveling mechanism constructed in accordance with this invention;

FIG. 5 is an enlarged view of the control cab and its connection to the gantry;

FIG. 6 is a view taken generally along lines 66 of FIG. 5;

FIG. 7 is a partial side or athwartship view of an alternative arrangement of this invention;

FIG. 8 is a partial, slightly enlarged view of the swing damping arrangement for the installation of FIG. 7; and

FIG. 9 illustrates a hook-type load engaging mechanism suspended from a listing ship.

With particular reference to the drawings, this invention is illustrated as being incorporated in a shipboard cargo handling crane which includes a pair of C-shaped gantries 10 and 12, each of which carries a movable boom 14 and 16. In a manner well known in the art, the gantries are mounted for movement fore and aft of the ship on rails 18 and 20 and booms 14 and 16 are mounted for movement athwartship on gantry rollers 38. Each boom carries a load trolley 22 which supports load engaging means such as spreader 24 and, in a manner to be described more completely hereinafter, the load trolley is supported for movement with and with respect to the booms so that it can be positioned over one of the hatches 26, 28 and 30 or to either the port or starboard side of the ship. In this manner, cargo can be transported between cargo holds 32, 34 and 36 and a point remote from the ship.

With particular reference to FIGS. 1, 2 and 3, the construction of the gantries and booms will be described and since both gantries, booms and their interconnection are identical only one such arrangement will be described. Pairs, of rollers 38 are supported from the gantry in relatively spaced relationship along the longitudinal axis of the gantry and are arranged to engage opposed sides of boom 16 to support the boom for movement athwartship.

The boom drive is of well known construction compris-' ing pinions 40 powered by a drive mechanism 42 and engaging gear racks 44 and 46 on the boom so that rotation of pinions 40 produces athwartship movement of the boom.

Load trolley 22 includes relatively spaced pairs of rollers 48 which engage boom 16 so that the load trolley is supported for movement with and with respect to boom 16. Preferably, the load trolley is arranged for synchronized movement with the boom but, if desired, it can be mounted for independent movement relative to the boom in a manner well known in the art. In the illustrated embodiment (see FIG. 4) the synchronized movement of the load trolley relative to the boom is obtained through a cable reeving arrangement wherein a cable Stl has one end anchored to the gantry at point 52, for example connected to transverse gantry member 54, and extends over sheave 56 located at the left end of boom 16 and is anchored at a point 58 on the load trolley. A- second cable 60 has one end anchored at a point 62, on gantry cross member 64, extends over a sheave 66 located at the righthand end of the boom and is anchored at a point 68 on the load trolley. In this manner the load trolley is connected through constant lengths of cable extending between the load trolley and the gantry and reeved on the movable boom so that as the boom is racked athwartship the movement of the boom relative to the gantry produces movement of the load trolley relative to the boom as well as with respect to the gantry.

The hoist mechanism for spreader 24 includes a hoist drum 70 supported on the gantry and powered from a suitable source 72 also mounted on the gantry. The hoist mechanism also includes first hoist cable 74 which extends from drum 70, over gantry sheave 76, below gantry sheave 78 and over she-ave 80 supported at the left end of boom 16. From boom sheave 80 cable 74 extends over load trolley sheave 82 and below spreader sheave 84 to an anchor point 86 on the load trolley. Hoist cable 88 extends from the hoist drum over gantry sheave 90 to gantry sheave 92 and from gantry sheave 92 to sheave 94 supported at the right end of boom 16. From boom sheave 94, cable 88 extends along the boom, over load trolley sheave 96 and under spreader sheave 98 to an anchor point 100 on the load trolley. With this arrangement counterclockwise rotation of the drum will raise the spreader and, conversely, clockwise rotation of the drum will lower the spreader. Furthermore, the hoist cables 74 and 88, being fixed at their opposed ends relative to the gantry and on the load trolley, comprise constant lengths of cable reeved on the boom and load trolley so that the vertical height of the spreader is not affected by movement of the boom and load trolley along the gantry.

FIG. 7 illustrates load handling apparatus identical to that just described in connection with FIGS. 1-3 except in that it includes hook-type load engaging mechanisms. More particularly, hoist cable 170 extends from hoist drum 172, again mounted on the gantry, over gantry sheave 174, under gantry sheave 176 to boom sheave 178 and over trolley sheave 180 to oneside of hook 182. Hoist cable 184 extends from the hoist drum, over gantry sheave 186, over gantry sheave 138 and boom sheave 190, and over trolley sheave 192 to the opposite side of the hook. Rotation of drum 172 will either raise or lower hook 182 with respect to the load handling apparatus as desired and, when drum 172 is at rest and hook 182 is positioned at a desired elevation, the hook is in effect supported by constant lengths of cable which are reeved on the boom and the trolley so that the hook will maintain that elevation during relative movement between the load trolley, support boom and the gantry.

In the use of shipboard cranes, two commonly encountered conditions which must be corrected for are a listing ship and a swinging load. In accordance with this invention, both these conditions are preferably corrected through the selective operation of a swing damping and load leveling assembly 102 which is associated with and acts directly through the hoist cables. With particular reference to FIGS. 3 and 4a, assembly 102 includes a cable 114 extending from drum 116 and having its opposed ends connected to yokes 110 and 112 which are connected to gantry sheaves 76 and 90. Sheaves 76 and 90 can be mounted on the gantry in any manner well known in the art for movement between the dotted line positions illustrated in FIG. 2. For exam- .ple, a sheave can be carried on a shaft suitably journaled in the sheaves for rotation relative thereto and with the shaft supported by suitably arranged rollers which are confined on the gantry for movement in the direction of movement of the hoist cables. The swing damping portion of assembly 102 takes the form of a double acting hydraulic cylinder 118 of conventional construction and illustrated schematically in FIG. 4a. As is well known the hydraulic cylinder assembly includes a valve arrangement 119 connected to the cylinder interior on opposite sides of piston 122 through conduits 121 and 123 (the valve arrangement could be contained within the cylinder but for purposes of better illustration has been shown exteriorly). Piston 122 is connected to drum shaft 126 by connecting rod 125 and lever 124 which is in turn fixed to and movable with the drum shaft. Shaft 126 is movable with the drum, and the double acting cylinder, suitably anchored relative to the gantry, opposes movement of the drum in both directions. The load leveling portion of assembly 102 is operated off of a drum shaft 128 extending from the opposite end of drum 116 and connected to a reversible motor 130 through drive means 132 and a clutch 134. By engaging clutch 134 and energizing motors 130, drum their traveL- It will be appreciated that after the load leveling assembly has been operated to adjust a load with respect to a listing ship lever 124 and piston 122 will have assumed a different null position within their range of travel.

With the spreader in use, it may become necessary,

for example where the ship is listing during a loading or unloading operation, to adjust the horizontal position of the spreader and this is accomplished through the operation of the load leveling portion of assembly 102. More particularly, by engaging clutch 134 and energizing motor drum 116 can be rotated either clockwise or counterclockwise as desired. Assuming counterclockwise rotation, sheave 90 will be moved to the right (as viewed in the drawings) and, through hoist cable 88, spreader sheave 98 will be moved upwardly. Simultaneously, cable 114 will be paid out to sheave 76 allowing spreader sheave 84 to move downwardly. Thus, by manipulating hoist cables 74 and 88 through rotation of drum 116 and movement of sheaves 76 and 90, the spreader can be adjusted horizontally as desired. Furthermore, where two booms are utilized as illustrated in FIG. 1 and with the spreader being associated with a leveling arrangement as just described, fine and exact control over the horizontal position of the spreader and/or load is possible. For example, with containerized cargo and a spreader, the spreader can be adjusted about an athwartship axis by the separate hoist mechanisms and each end of the spreader can be adjusted about a fore and aft axis through the leveling portion of mechanism 162.

The leveling portion of assembly 102 will perhaps find its widest and most significant utility when used in combination with a spreader and, similarly, the damping portion will perhaps find its greatest utility when used in combination with a hook-type load engaging mechanism. Therefore, an explanation of the swing damping portion of assembly 102 will be made with particular reference to the load handling apparatus of FIGS. 7 and 8 which includes hook-type load engaging mechanism, FIG. 8 also illustrating an alternative connecting arrangement between sheaves 174 and 186 and the hydraulic damping cylinder. In this arrangement, gantry sheaves 174 and 186, mounted for movement in the manner discussed above in relation to sheaves 76 and 90, are connected by yoke-s 191 and 193 and cables 195 and 197 to relatively spaced points on lever 194. Lever 194 is pivotally supported intermediate the points of connection with the sheaves by a bracket 196 which is fixed to the gantry. Double acting cylinder 198 is connected to one end of the lever 194 and is arranged to oppose both clockwise and counterclockwise movement of the lever about its pivot point. When the hook, and load assume a normal, vertical non-swinging position, sheaves 174 and 186 will be aligned and lever 194 will assume the position illustrated in FIG. 8. When the hook swings in the direction of the longitudinal axis of boom 16, hoist cables and 184 are alternately subjected to a slack condition and an increased tension condition. Assuming the load to be swinging inwardly toward the gantry, a force in a payout direction is exerted on hoist cable 170, ie, the tension on hoist cable 170 is increased.

vThis tends to move sheave 174 to the leftand pivot lever 194 counterclockwise as viewed in the drawings. This pivotal movement of lever 194 is opposed by the hydraulic cylinder, and, correspondingly, movement of sheave 174 and payout of cable 170 are opposed thereby achieving a damping effect on the swinging movement of the hook. Simultaneously with an increase in tension on cable 1741, cable 184 will have gone slack and it will be noted that the counterclockwise pivotal movement of lever 194 will have moved sheave 186 to the right to take up the slack cable. Similarly, with the hook swinging outwardly of the gantry, the tension on cables 184 will increase and the lever will tend to rotate clockwise, this movement again being opposed by the hydraulic cylinder and a damping action being achieved. Accordingly, lever 194 will alternately be pivoted clockwise and counterclockwise as the load swings with the double acting cylinder opposing movementin both directions to provide a damping force and eventually bring the hook to rest, and accomplishing this while simultaneously accommodating slack cable.

As illustrated in FIG. 8 the mechanism connected to movable sheave 174 and 186 includes only the double acting hydraulic cylinder for effecting the damping action but does not include a leveling arrangement comparable to that illustrated in FIG. 4a, however, a leveling arrangement could be provided by connection with the opposite end of lever 94. The arrangement of FIG. 8 is advantageous for use in combination with load engaging mechanism of the hook-type, since the load leveling operation is of major significance only when used in connection with a spreader. However, FIG. 4a does illustrate how a single assembly can be provided which will have universal applicability to load engaging mechanisms of both .the spreader and hook type. The operation of the leveling portion of assembly 102 has already been described in connection with the spreader and to complete this description it will be described in connection with FIGS. 4 and 4a. Assuming that a hook-type load engaging mechanism is connected to hoist cables 74 and 88 of FIGS. 4 and 4a, i.e. hoist cables 74 and 88 correspond to hoist cables 170 and 184 respectively, the operation of the damping portion of the assembly 102 will be described. Assuming the hook and load to be swinging inwardly toward the gantry, the tension on hoist cable 74 is increased moving sheave 76 to the left. This movement rotates drum 116 counterclockwise and tends to move lever 124 to the dotted line position 124a. Drum rotation is opposed by the hydraulic cylinder and, correspondingly, movement of sheaves 76 and payout of cable 74 are opposed to thereby damp the swinging movement of the hook and load. Simultaneously with movement of sheave 76 to accommodate the increased tension of hoist cable 74, sheave 90 will be moved to the right to accommodate the slack con dition of cable 88 which will be produced by the swinging hook. When the hook and load swing outwardly of the gantry, the tension on cable 88 is increased and the drum tends to rotate to the dotted line position 124b, again this movement is opposed by the hydraulic cylinder and a damping action being achieved. Drum 116 will alternately be rotated clockwise and counterclockwise as a result of the swinging movement of the hook and the double acting cylinder will oppose this movement in both directions to thereby elfect a damping action and eventually bring the hook and load to rest.

A further advantageous feature of the arrangement of the damping mechanism of both FIGS. 4a and 8 is that it provides an automatic equalization for hoist line loads and hoist line lengths to permit the hook and load to assume a plumb position when extending from a listing ship. As illustrated in FIG. 9, when the ship is listing the crane and trolley 22 will be disposed at an angle to the horizontal. However, the load and hook 182 will adjust to this condition so that the load assumes and maintains a horizontal position, but in doing so the normal equilibrium of the hoist cables 170 and 184 is disturbed. The double acting cylinder 198, acting through the hoist cables, accommodates the variation in angularity of the hoist cables. With a listing ship, rather than cables 170 and 184 extending equally from the trolley, the extension of cable 184 is greater than that of cable 170 (see FIG. 9). Sheave 186 moves to the left and sheave 174 to the right to accommodate this variation in extension. The piston in cylinder 198 is movable in response to movement of the sheaves and will assume a different null position within the cylinder corresponding to the condition of the hook mechanism. Hence, with this arrangement line load is equalized and the cylinder assumes a corresponding null position and is still effective to damp swinging action of the hook and load from the plumb position which the hook and load may have assumed.

In another aspect of this invention, it is contemplated to arrange the control cabs and 142 so that they can be movedon the gantries independently of the booms and load trolleys to thereby afford increased surveillance and control over the cargo loading and unloading operation. More particularly and with reference to FIGS. 5 and 6, control cab 142 includes a laterally extending bracket 144 which supports a vertical roller 146 which is in turn engaged in a channel-shaped track 148 on I-beam 150 which is a part of gantry 12. Roller 146 provides vertical support for cab 142 and horizontal support is provided by a lower roller 154 engaging lower flange 156 on I-beam 150 and a horizontal roller 152 also carried by bracket 144 and positioned Within track 148 for engagement with the vertical side walls thereof. The

vertical and horizontal rollers support the cab for movement relative to the gantry upon energization of a motor 164 mounted on the cab. To more specifically describe the drive arrangement, a rack 158 is supported on the upper flange 160 of the I-beam for engagement with a pinion 162 which is connected to motor 164 through suitable drive means 166. Accordingly energization of motor 164 rotates pinion 162 to move cab 142 along the gantry. The cab can then be independently moved to any desired position on the gantry to afford the operator a better view of a particular operation which is being carried on. For example, should it be necessary to level the load engaging apparatus, or align it with a load, the operator can move the cab to its outermost position on the gantry where he will be in the best vantage point for actuating the leveling arrangement, or as the load is being raised from or into one of the hatches the operator can position the control cab over the particular hatch to properly guide the load therethrough. It will be appreciated that the support arrangement and drive for both cabs is identical and therefore for convenience only one has been illustrated and described. The feature of the independently movable control cab is the subject of a co-pending application Serial No. 408,713, filed September 29, 1964 as a division of this application and also assigned to the assignee of this application.

Although this invention has been illustrated and described in connection with particular embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

What we claim is:

1. In load handling apparatus including load engaging means and hoist means including a pair of hoist cable means connectedto said load engaging means for raising and lowering said load engaging means along a generally vertical path the combination with said hoist cable means of sheave means supporting each ofsaid hoist cable means and mounted for movement in response to swinging movement of said load engaging means from said vertical path, in which said swinging movement exerts a force in a payout direction on one and produces a slack condition on the other of said hoist cable means, damping means including a movable member, means connecting said movable member to and for movement in accordance with said movement of said response to a force in a payout direction on one of said hoist cables is transmitted to the other of said sheaves for movement of said other sheave to accommodate said slack cable condition, and a damping member connected to and arranged to oppose movement of said movable member in response to movement of said sheave means, i

and means connected to and operable to move said movable member to selectively move one of said sheaves in a payout direction and the other of said sheaves in a heave direction to simultaneously payout one and heave the other of said hoist cable means.

2. The combination of claim 1 wherein said load engaging means comprises a spreader and said hoist cable means are connected to said spreader at relatively spaced points thereon.

3. In load handling apparatus including load engaging means and hoist means including a pair of hoist cable means connected to said load engaging means for raising and lowering said load engaging means along a generally vertical path the combination with said hoist cable means of sheave means supporting said hoist cable means and mounted for movement in response to swinging movement of said load engaging means from said vertical path, in which said swinging movement exerts a force in a payout direction on one and produces a slack conditionon the other of said hoist cable means,

and damping means including a movable member,

means connecting said movable member to and for movement in accordance with movement of said sheave means in response to swinging movement of said load engaging means, said movable member so arranged that movement of one of said sheaves in response to a force in a payout direction on one of said hoist cable means is transmitted to the other of said sheaves for movement of said other sheave to accommodate said slack hoist cable condition, and a clamping member in the form of a double acting cylinder connected to' and arranged to oppose movement of said movable member in response to movement of said sheave means, said damping member having a normal null position corresponding to a normal operating position of said load engaging means and being movable, in response to movement of said load engaging means from said normal operating position due to variations in the horizontal position of said load handling apparatus, to a second null position corresponding to an abnormal operating position of said hook mechanism.

4. The combination of claim 3 wherein said movable member comprises lever means and connecting cable means extending between each of said sheave means and said lever means and engaging said lever means at relatively spaced points thereon,

and means mounting said lever means for pivotal movement about a point intermediate the point of connection of said connecting cable means on said lever means.

5. In load handling apparatus including load engaging means and hoist means including hoist cable means for raising and lowering said load engaging means along a generally vertical path the combination of means supporting said hoist cable means and arranged for movement in response to swinging movement of said load engaging means from said vertical path and supporting said hoist cable means for movement relative to said supporting means to raise and lower said load engaging means,

damping means operative to oppose movement of said support means due to said swinging movement, adjusting means for selectively moving said support 8 means to payout and heave said hoist cable means and adjust the horizontal position of said load engaging means, and means connecting both said damping and adjusting means to said support means so that said damping and adjusting means act on said support means through the same medium. 6. In load handling apparatus including load engaging means and hoist means including hoist cable means for 0 raising and lowering said load engaging means along a generally vertical path the combination of first means connected directly to said hoist cable means and supported for movement with said hoist cable means in response to swinging movement of said load engaging means from said vertical path and supporting said hoist cable means for movement relative to said first means to raise and lower said load engaging means,

and damping means connected to said first means and arranged to exert a force on said hoist cable means in opposition to movement of said hoist cable means due to said swinging movement and thereby damp swinging movement of said load engaging means from said vertical path.

7. In load handling apparatus including load engaging means and hoist means including hoist cable means connected to said load engaging means for raising and lowering said load engaging means along a generally vertical path the combination of first means connected directly to and supporting said hoist cable means for movement with respect to said first means to raise and lower said load engaging means,

means mounting said first means in said load handling apparatus for movement with said hoist cable means in response to swinging movement of said load engaging means from said vertical path,

and damping means connected to said first means and arranged to exert a force on said first means in opposition to the force exerted on said hoist cable means in a payout direction due to swinging movement of said load engaging means and thereby damp swinging movement of said load engaging means from said vertical path.

8. In load handling apparatus including load engaging means and hoist means including a pair of hoist cable means connected to said load engaging means for raising and lowering said load engaging means along a generally vertical path the combination with each of said hoist cable means of sheave means supporting each of said hoist cable means,

means connecting said sheave means in said load handling apparatus and supporting said sheave means for movement with said hoist cable means in response to swinging movement of said load engaging means from said vertical path, in which said swinging movement exerts a force in a payout direction on one and produces a slack condition on the other of said cable means,

and damping means connected to said sheave means and arranged to exert a force on said sheave' means in opposition to movement of said sheave means in response to a force on said hoist cable means in a payout direction due to swinging movement of said load engaging means.

9. In load handling apparatus including load engaging means and hoist means including a pair of hoist cables connected to said load engaging means for raising and lowering said load engaging means along a normal vertical path the combination with said hoist cables of a sheave supporting each of said hoist cables,

means mounting said sheaves for movement with said hoist cable means in response to swinging movement of said load engaging means from said normal vertical path and including a rotatable drum and connecting cable means wound on andhaving end portions 9 extending from said drum to each of said sheave means in oppositely wound relation with respect to said drum and arranged so that movement of said sheaves in response to swinging movement of said load engaging means rotates said drum to move said cable means end portions in opposite directions,

and damping means connected to and arranged to oppose rotation of said drum so that swinging movement of said load engaging means from said normal vertical path moves one of said sheaves in a direction to payout one of said hoist cables and rotates said drum with said drum rotation simultaneously moving the other of said sheaves in a direction to heave the other of said hoist cables so that said damping means opposes swinging movement and accommodates slack hoist cable produced by said swinging movement.

10. The combination of claim 9 including means connected to and operative to selectively rotate said drum in either of two directions to move said sheaves and heave one of said hoist cables while paying out the other of said hoist cables to adjust the horizontal position of said load engaging means.

11. In load handling apparatus including load engaging means and hoist means including a pair of hoist cable means connected to said load engaging means for raising and lowering said load engaging means along a generally vertical path the combination with each of said hoist cable means of sheave means supporting each of said hoist cable means,

means connecting said sheave means in' said load handling apparatus and supporting said sheave means for movement with said hoist cable means in response to swinging movement of said load engaging means from said vertical path, in which said swinging movement exerts a force in a payout direction on one and produces a slack condition on the other of said cable means,

and damping means including a movable member, means connecting said movable member to and for movement in accordance with said movement of said sheave means in response to swinging movement of said load engaging means, said movable member so arranged that movement of one of said sheaves in response to a force in a payout direction on one of said hoist cable means is transmitted to the other of said sheaves for movement of said other sheave in a heave direction to accommodate said slack cable condition, and a damping member connected to and arranged to oppose movement of said movable mem ber and thereby damp swinging movement of said load engaging means.

References Cited by the Examiner UNITED STATES PATENTS 1,491,424 4/1924 Robertson 212-21 2,003,255 5/1935 Duff 254189 X 2,013,170 9/1935 Penote 37-144 2,020,306 11/1935 Fitch 254168 X 2,139,772 1271938 Ringe 212-21 2,588,037 3/1952 Orton 254-172 X 2,805,781 9/1957 Senn.

2,811,262 10/1957 Schaitberger 254-168 X 2,916,162 12/1959 Gercke.

2,947,096 8/1960 Cummings 37-144 3,065,862 11/1962 Patterson.

3,074,563 1/1963 Montgomery 212-15 3,077,992 2/1963 Bevard 21215 3,102,642 9/1963 Zweifel 21215 3,107,791 10/1963 Michael 21258.1

SAMUEL F. COLEMAN, Primary Examiner.

ANDRES H. NIELSEN, Examiner.

A. LEVINE, Assistant Examiner. 

1. IN LOAD HANDLING APPARATUS INCLUDING LOAD ENGAGING MEANS AND HOIST MEANS INCLUDING A PAIR OF HOIST CABLE MEANS CONNECTED TO SAID LOAD ENGAGING MEANS FOR RAISING AND LOWERING SAID LOAD ENGAGING MEANS ALONG A GENERALLY VERTICAL PATH THE COMBINATION WITH SAID HOIST CABLE MEANS OF SHEAVE MEANS SUPPORTING EACH OF SAID HOIST CABLE MEANS AND MOUNTED FOR MOVEMENT IN RESPONSE TO SWINGING MOVEMENT OF SAID LOAD ENGAGING MEANS FROM SAID VERTICAL PATH, IN WHICH SAID SWINGING MOVEMENT EXERTS A FORCE IN A PAYOUT DIRECTION ON ONE AND PRODUCES A SLACK CONDITION ON THE OTHER OF SAID HOIST CABLE MEANS, DAMPING MEANS INCLUDING A MOVABLE MEMBER, MEANS CONNECTING SAID MOVABLE MEMBER TO AND FOR MOVEMENT IN ACCORDANCE WITH SAID MOVEMENT OF SAID SHEAVE MEANS IN RESPONSE TO SWINGING MOVEMENT OF SAID LOAD ENGAGING MEANS, SAID MOVABLE MEMBER SO ARRANGED THAT MOVEMENT OF ONE OF SAID SHEAVES IN RESPONSE TO A FORCE IN A PAYOUT DIRECTION ON ONE OF SAID HOIST CABLES IS TRANSMITTED TO THE OTHER OF SAID SHEAVES FOR MOVEMENT OF SAID OTHER SHEAVE TO A ACCOMMODATE SAID SLACK CABLE CONDITION, AND A DAMPING MEMBER CONNECTED TO AND ARRANGED TO OPPOSE MOVEMENT OF SAID MOVABLE MEMBER IN RESPONSE TO MOVEMENT OF SAID SHEAVE MEANS, AND MEANS CONNECTED TO AND OPERABLE TO MOVE SAID MOVABLE MEMBER TO SELECTIVELY MOVE ONE OF SAID SHEAVES IN A PAYOUT DIRECTION AND THE OTHER OF SAID SHEAVES IN A HEAVE DIRECTION TO SIMULTANEOUSLY PAYOUT ONE AND HEAVE THE OTHER OF SAID HOIST CABLE MEANS. 